The present invention relates to a protective element. Such an element may be incorporated within protective clothing, such as shinpads and ankle protectors, jackets, footwear and helmets. The protective element may also be incorporated in containers, luggage bags or suitcases in order to protect the contents thereof.
Known shinpads typically comprise a plastic outer shell with a soft foam backing for comfort. Such a design does not cater for shock load energy management. Furthermore, the protective outer element can become damaged without the user knowing that such damage has occurred. Thus the protection offered by the pad to subsequent impact is reduced.
According to a first aspect of the present invention, there is provided a protective element comprising a first layer arranged adjacent a multicelled element, and in which the multicelled element can be visually inspected.
The multicelled element acts as a main energy absorbing and dissipating element.
Preferably the multicelled element is a honeycomb element. However, the term xe2x80x9choneycomb elementxe2x80x9d should be construed broadly to included structures having any shape of open cell with adjacent cells separated by walls. Thus the cells can have almost any shape, for example circular, hexagonal, rectangular, elliptical, square, trapezium, trapezoid or irregular. Furthermore, the walls need not be of uniform thickness, either across the surface of the protective element, nor in the direction perpendicular to the local surface of the protective element.
Preferably a second layer is also provided, the fist and second layers being arranged on opposite sides of the multicelled element. Thus the multicelled element forms a core of the protective element.
Preferably the protective element is arranged such that, in use, the first layer faces xe2x80x9coutwardlyxe2x80x9d towards a direction of threat and the second layer faces xe2x80x9cinwardlyxe2x80x9d towards the item being protected.
Preferably the first layer acts as an outer skin which transmits the load of any impact to the multicelled element. The second layer may form an inner skin which acts as a support for the multicelled element.
Preferably the outer layer is thicker than the inner layer in order to give it improved resistance to impact loads and resistance to other damage that may occur during normal use. Preferably the first layer is a thermo-plastic material, such as polycarbonate, polypropylene or ABS tec. Alternatively the first layer may be a reinforced plastic material consisting of high tensile fibres, such as carbon, glass, kevlar or dyneema embedded in a thermosetting resin such as an epoxy or a thermoplastic resin such as polyetherimide.
The inner layer may comprise a foam in order to provide a relatively soft surface in contact with the item to be protected. Additionally or alternatively the inner layer may also comprise the same materials as the outer layer.
The multicelled element could be made of any suitable material, such as metals, commonly aluminium, plastic, glass, reinforced plastics, thermoplastics, composites containing fibres embedded in a plastic matrix or paper. The combination of multicelled element materials, thickness, and materials used in the first and second layers may be varied to tune the response of the protective element to specific dynamic impact loads. Furthermore, the construction of the multicelled element may be varied by using different materials, different density or cell size or cell shape to vary the crush load.
Advantageously the protective element is covered with a further layer of abrasion resistant material such as nylon or kevlar, which is selectively removable.
Advantageously the protective element is incorporated within protective clothing, such as a leg pad, shinpad, ankle pad, jacket or helmet. The protective clothing may be designed to hold the protective elements in pockets, such that the protective element can be replaced in the event of damage or removed if it is not required.
The protective element may also be incorporated within footwear, for example in the tongue of a boot, or in an insole. Thus a sports boot may be provided with a tongue incorporating the protective element. Sports boots, such as football boots are generally required to be securely laced to the wearer""s feet. A tongue incorporating the protective element will help distribute the load produced by the boot fastenings, such as laces, more evenly across the top of the foot, thereby making the boot more comfortable. Additionally, tests have indicated that a boot incorporating such an element can give rise to a better kick. It is believed that reversible deformation within the protective element allows the contact time with the ball to be increased and that enhances direction and power of a kick.
Additionally the protective element will reduce the risk of broken bones in the event that the foot is stamped upon.
Sport boots may have studs formed in the sole thereof to enhance grip. This can give rise to areas of increased rigidity within a boot which, in turn, can cause blisters. The provision of an insole incorporating a protective element can alleviate the problem since the protective element spreads the load generated near the studs and also cushions the foot.
Advantageously at least one of the first and second layers is transparent or translucent. This enables the condition of the multicelled element to be visually inspected. If both layers are transparent or translucent then light can pass through the layers and through the cells bounded by the walls of the multicelled element. Permanent damage to the multicelled core causes deformation of the walls which in turn closes the holes within the multicelled element. Thus the amount of light transmitted through the multicelled element is reduced in damaged areas of the element. Similarly if the multicelled element is viewed in reflected light, the proportion of light reflected by damaged areas of the multicelled element is greater than that reflected by undamaged areas. However, in hose embodiments only having one layer adjacent the multicelled element, the element can be directly inspected to identify any damage, such as crushing, of the element.
The multicelled element may be coloured or coated such that its colour changes as a result of sustaining damage. The multicelled element may be coated with a thin layer which provides a visually attractive surface to an undamaged multicelled element and which allows damaged areas to be quickly identified by virtue of a change in the colour or reflective properties of the damaged area. One mechanism for the colour change is that the thin layer becomes damaged and ruptured allowing the colour of the underlying material to be viewed.
Alternatively a pressure sensitive layer or film may be provided adjacent to or on the multicelled element. Thus, for example, in an embodiment of the present invention having a multicelled element between first and second layers, where the first layer faces a direction of threat and the multicelled element is visible therethrough, a pressure sensitive layer may be disposed between the multicelled element and the second layer.
The pressure sensitive layer is arranged to release a pigment when the pressure, i.e. force per unit area, exceeds a predetermined pressure. A suitable pressure indicating film is commercially available under tile trade mark PRESSUREX from Fuji paper and may be purchased via Sensor Products Inc. of 188 Rt10, Ste 307, East Hanover, N.J. 07936-2108 USA. The film comes in five pressure ranges, and the indicating force at which the pigment is released can be tailored be selecting an appropriate film and by varying the contact area between the multicelled element and the pressure sensitive layer.
Preferably the thickness of the protective element is between 9 mm and 3 mm. Advantageously the diameter of the cells in the multicelled element are similar to the thickness of the protective element, say in the range of 3 to 9 mm. These dimensions are particularly suited for use in shinpads. However other thicknesses and cell diameters may be selected depending on the specific application.
Preferably the density of the honeycomb core is in the region of 80 kgmxe2x88x923. This density has been found to provide an appropriate level of transverse stiffness. Too high a density results in the protective element transmitting force too readily, whereas too low a density causes it to act like a spring.
A xe2x80x9cfull facexe2x80x9d shinpad constituting an embodiment of the present invention comprises an outer membrane skin of impact resistant material bonded to a honeycomb core. The outer layer and honeycomb core are constructed to have some flexibility in a first direction so that the pad can be adjusted to fit the leg of the user. The inner layer comprises a thin foam layer in order to give structural stability to the pad and to make the pad comfortable to wear. For a segmented shinpad, a plurality of protection elements may be provided as strips which are held in pockets.
According to a second aspect of the present invention, there is provided protective clothing comprising a protective element according to the first aspect of the present invention.
As used herein, the term clothing includes footwear and headwear.